Guide Chip Structure for High-Frequency Induction Heating Coil

ABSTRACT

To provide a structure of guide chips for high frequency induction heating coil which makes it possible to correctly position the guide chips for high frequency induction heating coil in the width direction of a journal portion or a pin portion of a crankshaft and which thus makes it possible to correctly position a semi-open saddle type high frequency induction heating coil in the width direction of the journal portion or the pin portion. 
     Each of guide chips  21   a  to  21   c  includes: respective pairs of flexible bodies  24   a  to  24   c , which pair are respectively provided in side plates  7  and  7 , and have a spring function; a pair of chips  29   a  and  29   a  which are arranged and fixed in the inside of the pair of flexible bodies facing each other; and a pair of chip fixing plates  30   a  and  30   a  which are respectively arranged and fixed in the inside the pair of chips. Furthermore, the guide chips  21   a  to  21   c  are also configured such that in a free state, a gap  32  exists between the inner surfaces of the pair of chip fixing plates, and also the width dimension between the external surfaces of the pair of chips is set to become larger than the width dimension of a journal portion  2  or a pin portion  4 , and such that when the guide chips are inserted between counterweight portions  3  and  3  adjacent to each other, the gap  32  is reduced or eliminated by the spring function of the pair of flexible bodies.

TECHNICAL FIELD

The present invention relates to a structure of a plurality of guidechips for high frequency induction heating coil which are respectivelyattached between a pair of side plates for supporting a semi-open saddletype high frequency induction heating coil, and which, when a journalportion or a pin portion of a crankshaft is subjected to high frequencyinduction heating by the semi-open saddle type high frequency inductionheating coil, are used for positioning the center of the journal portionor the pin portion with respect to the semi-open saddle type highfrequency induction heating coil, and used for positioning the semi-opensaddle type high frequency induction heating coil in the width directionof the journal portion or the pin portion between mutually adjacentcounterweight portions of the crankshaft. More particularly, the presentinvention relates to a structure of a plurality of guide chips for highfrequency induction heating coil in which the structure enables thenon-hardened area of the hardened case formed in the journal portion orthe pin portion to fully satisfy the range of the specification.

BACKGROUND ART

As shown in FIG. 9, a crankshaft 1 which is an object to be heated isconfigured by a journal portion 2 serving as a central shaft,counterweight portions 3 arranged between the journal portions 2adjacent to each other, and a pin portion 4 provided between thecounterweight portions 3 facing each other, and the like. The journalportion 2 and the pin portion 4 are subjected to high frequencyinduction heating so as to be hardened. As the hardening methods, thereare flat hardening and filet R hardening. In any of the methods, ahardened case needs to be correctly formed in the journal portion 2 orthe pin portion 4. Note that as a high frequency induction heatingapparatus for applying high frequency induction heating to the journalportion 2 or the pin portion 4, there is conventionally adopted, forexample, an apparatus as shown in FIG. 1 of Japanese Patent Laid-OpenNo. 2002-226919 (patent document 1).

The high frequency induction heating apparatus as described in JapanesePatent Laid-Open No. 2002-226919 is configured as shown in FIG. 1 inJapanese Patent Laid-Open No. 2002-226919. FIG. 10 shows a highfrequency induction heating apparatus 6 which is similar to theapparatus shown in FIG. 1 in Japanese Patent Laid-Open No. 2002-226919,and which uses a semi-open saddle type high frequency induction heatingcoil 5.

As shown in FIG. 10, the high frequency induction heating apparatus 6includes a pair of side plates 7 which are connected to the apparatusmain body side so as to be arranged to face each other, the semi-opensaddle type high frequency induction heating coil 5 which is arranged ina lower end side opening portion of the side plate 7 so as to besupported by the side plate 7, guide chips 8 a, 8 b and 8 c for highfrequency induction heating coil which are arranged at predeterminedplaces (in the present example, three places of the upper side portionwith respect to the center line of the journal portion 2 of thecrankshaft 1, and of the left and right side portions with respect tothe center line of the journal portion 2) corresponding to the semi-opensaddle type high frequency induction heating coil 5, so as to beattached to the side plate 7, and the like. Furthermore, in the highfrequency induction heating apparatus 6, a power supply lead conductor 9is connected to the semi-open saddle type high frequency inductionheating coil 5, and cooling water supply means 10 for quickly cooling aheated portion of the crankshaft 1, and the like, is provided. The guidechips 8 a, 8 h and 8 c for high frequency induction heating coil aremembers provided so that a predetermined gap (about 0.5 mm to 3.5 mm) issecured between the journal portion 2 (or the pin portion 4) of thecrankshaft 1 and the semi-open saddle type high frequency inductionheating coil 5 at the time when the journal portion 2 (or the pinportion 4) is subjected to high frequency induction heating by thesemi-open saddle type high frequency induction heating coil 5. Inaddition, the guide chips 8 a, 8 b and 8 c are configured such that thesemi-open saddle type high frequency induction heating coil 5 ismounted, via the guide chips 8 a, 8 b and 8 c, on the journal portion 2(or the pin portion 4) which is rotated about the axis line of thecrankshaft 1 (the center line of the journal portion 2). At this time,the center of the journal portion 2 (or the pin portion 4) is positionedwith respect to the semi-open saddle type high frequency inductionheating coil 5 by abutting action of the guide chips 8 a, 8 b and 8 c onthe outer peripheral surface of the journal portion 2.

-   Patent document 1: Japanese Patent Application Laid-Open No.    2002-226919

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The guide chips 8 a, 8 b and 8 c for high frequency induction heatingcoil which are provided in the conventional high frequency inductionheating apparatus 6 having the above-described structure are usuallyconfigured by components as shown in FIG. 11( a) and FIG. 11( b). Thatis, each of the guide chips 8 a, 8 b and 8 c is configured by the sideplates 7 and 7 which are arranged so as to face each other via a gap 11,chips 12 and 12 which are respectively arranged in contact with theinner surfaces of the side plates 7 and 7, a chip fixing plate 13provided between the chips 12 and 12, screws 14 and 14 which integrallyand closely fix the side plates 7 and 7, the chips 12 and 12, and thechip fixing plate 13 to each other, and the like. Here, the widthdimension L₁ (see FIG. 11( a)) between the outer surfaces of the chips12 and 12 is fixed (cannot be changed), and hence it is necessary tomake the width dimension L₁ almost equal to the width dimension L₂ or L₃(see FIG. 9) of the journal portion 2 or the pin portion 4 of thecrankshaft 1.

However, in the case in which the width dimension L₁ is made completelyequal to, for example, the width dimension L₂ of the journal portion 2,when the guide chips 8 a, 8 b and 8 c are inserted between thecounterweight portions 3 and 3 on both sides of the journal portion 2 soas to be mounted on the journal portion 2, the guide chips 8 a, 8 b and8 c are not smoothly inserted. Thus, the width dimension L₁ must be setslightly smaller than the width dimension L₂. Furthermore, even if thereare used the guide chips for high frequency induction heating coil,which have the same width dimension L₁ as the width dimension L₂ of ajournal portion 2 of a crankshaft 1 of a certain type, in the case inwhich the same guide chips for high frequency induction heating coil arealso used for a crankshaft 1 of another type which has substantiallysimilar dimensions and in which the journal portion 2 has the sameoutside diameter dimension but has a width dimension slightly largerthan the width dimension L₂, a gap is generated between thecounterweight portion 3 of the crankshaft 1 and the guide chip for highfrequency induction heating coil. FIG. 12(a) shows a state in which agap δ is generated between the outer surface of the chip 12 and theinner surface of the counterweight portion 3, and shows a case in whichthe gap δ is generated because the width dimension L₁ of the guide chip8 a (and 8 b, 8 c) for high frequency induction heating coil is smallerthan the width dimension L₂ of the journal portion 2. In this case, thesemi-open saddle type high frequency induction heating coil 5 isarranged so as to face the outer peripheral surface of the journalportion 2 at a position shifted from the width-direction centralposition of the journal portion 2 similarly to the guide chip 8 a (and 8b, 8 c) for high frequency induction heating coil.

When the outer peripheral surface of the journal portion 2 is subjectedto high frequency induction heating for flat hardening while thecrankshaft 1 is rotated about the axis line thereof (the center line ofthe journal portion 2) in the state in which the gap δ exists asdescribed above, a hardened case S₁ is formed at a position shifted fromthe center in the width direction of the journal portion 2 (for example,at a position shifted to the right side) as shown in FIG. 12( b). Thiscauses a problem in that the dimensions α and β between each end portionof the hardened case S₁ and the inner surfaces of the counterweightportion 3 are different from each other. The dimensions α and β arereferred to as “non-hardened areas”, and a specification is specifiedfor the dimension. However, there arises a case in which the dimensionsα and β do not satisfy the specification.

Furthermore, in the case in which the outer peripheral surface of thejournal portion 2 is subjected to high frequency induction heating forfillet R hardening while the crankshaft 1 is rotated about the axis linethereof, when there is the gap δ between the guide chip 8 a (and 8 b, 8c) for high frequency induction heating coil and the counterweightportion 3 of the crankshaft 1 as shown in FIG. 12( c), the guide chip 8a (and 8 b, 8 c) for high frequency induction heating coil is notcorrectly positioned in the width direction of the journal portion 2.Therefore, the semi-open saddle type high frequency induction heatingcoil 5 is also not correctly positioned, so as to thereby cause adifference between case depths t₁ and t₂ at corner portions of ahardened case S₂ formed by the fillet R hardening, as shown in FIG. 12(d). As a result, there arises a case in which the values of the casedepths t₁ and t₂ do not satisfy the specification.

The present invention has been made in order to solve theabove-described problem. An object of the present invention is toprovide the structure of the guide chips for high frequency inductionheating coil, in which structure the guide chips for high frequencyinduction heating coil can always be correctly positioned in the widthdirection of the journal portion or the pin portion of the crankshaft,and hence the semi-open saddle type high frequency induction heatingcoil 5 can always be correctly positioned in the above-described widthdirection, and in which structure the non-hardened area in the case offlat hardening, and the case depth at the corner portion of the hardenedcase in the case of fillet R hardening can satisfy the specifications,and thereby the precise hardening can be performed.

Means for Solving the Problems

In order to achieve the above-described object, according to the presentinvention, there is provided a structure of a plurality of guide chipsfor high frequency induction heating coil, which are respectivelyattached between a pair of side plates for supporting a semi-open saddletype high frequency induction heating coil, which when a journal portionor a pin portion of a crankshaft is subjected to high frequencyinduction heating by the semi-open saddle type high frequency inductionheating coil, are used for positioning the center of the journal portionor the pin portion with respect to the semi-open saddle type highfrequency induction heating coil, and which are used for positioning thesemi-open saddle type high frequency induction heating coil in the widthdirection of the journal portion or the pin portion between the mutuallyadjacent counterweight portions of the crankshaft, the structure beingcharacterized in that the guide chip for high frequency inductionheating coil includes: a pair of flexible bodies which have a springfunction and are respectively provided in the pair of side plates; apair of chips which are respectively arranged and fixed in the inside ofthe pair of flexible bodies facing each other; and a pair of chip fixingplates which are respectively arranged and fixed in the inside of thepair of chips, and characterized by being configured such that, in afree state in which the guide chip for high frequency induction heatingcoil is not inserted between the mutually adjacent counterweightportions, a gap exists between the inner surfaces of the pair of chipfixing plates facing each other and thereby the width dimension betweenthe outer surfaces of the pair of chips facing each other is set largerthan the width dimension of the journal portion or the pin portion, andsuch that when the guide chip for high frequency induction heating coilis inserted between the mutually adjacent counterweight portions, thegap between the inner surfaces of the pair of chip fixing plates isreduced or eliminated by the spring function of the pair of flexiblebodies.

Furthermore, according to the present invention, it is configured suchthat the flexible body is integrally provided to the side plate byforming, in the side plate, a pair of slits that are arranged at adistance so as to face each other and that are extended to an openingportion of the side plate in which portion the journal portion or thepin portion is inserted and arranged.

Furthermore, according to the present invention, it is configured suchthat the guide chips for high frequency induction heating coil arearranged at three places of the upper side and the left and right sideswith respect to the center line of the journal portion or the pinportion, and such that the flexible body is provided at all or at leastone of the three places in which the three guide chips for highfrequency induction heating coil are arranged.

ADVANTAGES OF THE INVENTION

In the first aspect of the present invention, the guide chip for highfrequency induction heating coil includes: a pair of flexible bodieswhich have a spring function and are respectively provided in a pair ofside plates; a pair of chips which are respectively arranged and fixedin the inside of the pair of flexible bodies facing each other; and apair of chip fixing, plates which are respectively arranged and fixed inthe inside of the pair of chips, and is configured such that, in a freestate in which the guide chip for high frequency induction heating coilis not inserted between the mutually adjacent counterweight portions ofthe crankshaft, a gap exists between the inner surfaces of the pair ofchip fixing plates facing each other and thereby the width dimensionbetween the outer surfaces of the pair of chips facing each other is setlarger than the width dimension of the journal portion or the pinportion, and such that when the guide chip for high frequency inductionheating coil is inserted between the mutually adjacent counterweightportions, the gap between the inner surfaces of the pair of chip fixingplates is reduced or eliminated by the spring function of the pair offlexible bodies. Thus, with the structure of the guide chip for highfrequency induction heating coil according to the present invention, itis possible to obtain the following operation effects. That is, theguide chip for high frequency induction heating coil is configured as aflexible member (whose width dimension can be changed). Thus, when theguide chip for high frequency induction heating coil is inserted betweenthe counterweight portions adjacent to each other in the width directionof the journal portion or the pin portion, the guide chip for highfrequency induction heating coil, which has, in the free state, thewidth dimension larger than the width dimension between the mutuallyadjacent counterweight portions, is elastically deformed so that the gapbetween the inner surfaces of the pair of chip fixing plates is reducedby the spring function of the flexible bodies of the side plates. As aresult, the pair of chips are inserted and arranged between the mutuallyadjacent counterweight portions, so as to be brought into press contactwith the respective counterweight portions. Thereby, the guide chip forhigh frequency induction heating coil can always be correctly positionedin the width direction of the journal portion or the pin portion betweenthe mutually adjacent counterweight portions. Thus, the semi-open saddletype high frequency induction heating coil can always be correctlypositioned in the width direction of the journal portion or the pinportion. Thereby, the non-hardened area can be stably suppressed to bewithin the specification. Furthermore, by suitably setting the flexiblerange of the above-described flexible body, the same guide chip for highfrequency induction heating coil can also be used for a crankshaft inwhich the journal portion or the pin portion has the same outsidediameter dimension but has a slightly different width dimension.

Furthermore, in the second aspect of the present invention, it isconfigured such that the flexible body is integrally provided to theside plate by forming, in the side plate, a pair of slits which arearranged at a distance so as to face each other and which are extendedto the opening portion of the side plate in which portion the journalportion or the pin portion is inserted. Thus, it is not necessary toprovide a flexible body configured by a member which is separate fromthe side plate. Therefore, it is possible to facilitate themanufacturing of the high frequency induction heating apparatus.

Furthermore, in the third aspect of the present invention, it isconfigured such that the guide chips for high frequency inductionheating coil are arranged at three places of the upper side and the leftand right sides with respect to the center line of the journal portionor the pin portion, and such that the flexible body is provided at allor at least one of the three places in which the three guide chips forhigh frequency induction heating coil are arranged. Hence, it is obviousthat, when all the guide chips arranged at the three places are madeflexible, the guide chips for high frequency induction heating coil andthus the semi-open saddle type high frequency induction heating coil canbe surely positioned in the width direction of the journal portion orthe pin portion. Furthermore, even when at least one of the guide chipsarranged at the three places are made flexible, the above-describedpositioning in the width direction can be performed more correctly thanbefore, so that the non-hardened area can be suppressed to be within thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a high frequency induction heatingapparatus having a structure of guide chips for a high frequencyinduction heating coil according to an embodiment of the presentinvention;

FIG. 2 is a front view showing a side plate of the high frequencyinduction heating apparatus shown in FIG. 1, in a state in which theguide chips for high frequency induction heating coil are attached tothe side plate;

FIG. 3 shows a structure of the guide chip for high frequency inductionheating coil according to the present invention;

FIG. 3( a) is a sectional view of the guide chip for high frequencyinduction heating coil taken along the line A-A in FIG. 3( b);

FIG. 3( b) is a side view showing a place at which the guide chip forhigh frequency induction heating coil is attached to the side plate;

FIG. 4 shows a relationship of the guide chip for high frequencyinduction heating coil with a journal portion and a counterweightportion of a crankshaft;

FIG. 4( a) is a sectional view showing the guide chip for high frequencyinduction heating coil in a free state;

FIG. 4( b) is a sectional view showing a state in which the guide chipfor high frequency induction heating coil is inserted between themutually adjacent counterweight portions;

FIG. 5 is a sectional view showing a state in which a hardened case isformed in a portion without an oil hole in the journal portion by usingthe guide chip for high frequency induction heating coil according tothe present embodiment;

FIG. 6 is a sectional view showing a state in which a hardened case isformed in a portion with an oil hole in the journal portion by using theguide chip for high frequency induction heating coil;

FIG. 7 is a graph showing non-hardened areas formed in the portionwithout the oil hole in the journal portions by using the guide chip forhigh frequency induction heating coil according to the presentembodiment and by using a conventional guide chip for high frequencyinduction heating coil;

FIG. 8 is a graph showing non-hardened areas formed in the portion withthe oil hole in the journal portions by using the guide chips for highfrequency induction heating coil according to the present embodiment;

FIG. 9 is a side view of a crankshaft;

FIG. 10 is a side view showing a main portion of a high frequencyinduction heating apparatus having the conventionally configured guidechips for high frequency induction heating coil;

FIG. 11 shows a structure of the conventional guide chip for highfrequency induction heating coil;

FIG. 11( a) is a sectional view of the conventional guide chip for highfrequency induction heating coil taken along the line B-B in FIG. 11(b);

FIG. 11( b) is a front view of the conventional guide chip for highfrequency induction heating coil;

FIG. 12 is a sectional view showing a hardening method of the journalportion of the crankshaft, using the conventional guide chip for highfrequency induction heating coil;

FIG. 12( a) is a sectional view showing a state in flat hardening;

FIG. 12( b) is a sectional view showing a hardened case formed in thejournal portion by the flat hardening;

FIG. 12( c) is a sectional view showing a state in fillet R hardening;and

FIG. 12( d) is a sectional view showing a hardened case formed in thejournal portion by the fillet R hardening.

DESCRIPTION OF SYMBOLS

-   1 Crankshaft-   2 Journal portion-   3 Counterweight portion-   4 Pin portion-   5 Semi-open saddle type high frequency induction heating coil-   7 Side plate-   20 High frequency induction heating apparatus-   21 a, 21 b, 21 c Guide chip for high frequency induction heating    coil-   22 Semicircular arc-shaped opening portion-   23 Slit-   24 a, 24 b, 24 c Flexible body-   25, 26 Slit-   29 a Chip-   30 a Chip fixing plate-   31 a Screw-   32 Gap

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, there will be described a structure of guide chips fora high frequency induction heating coil according to an embodiment ofthe present invention with reference to FIG. 1 to FIG. 8. Note that inFIG. 1 to FIG. 8, the same portions as those in FIG. 9 to FIG. 12 aredenoted by the same reference numerals and characters, and the repeatedexplanation thereof is omitted.

FIG. 1 shows a high frequency induction heating apparatus 20 having astructure of guide chips for a high frequency induction heating coilaccording to an embodiment of the present invention. The high frequencyinduction heating apparatus 20 is configured to apply high frequencyinduction heating to a journal portion 2 of a crankshaft 1. As shown inFIG. 1, the high frequency induction heating apparatus 20 includes apair of side plates 7 which are respectively connected to the side of atransformer (not shown) and which are arranged so as to face each other,a semi-open saddle type high frequency induction heating coil 5 which isarranged at a lower end side opening portion of the side plate 7 so asto be supported by side plate 7, a power supply lead conductor 9 whichsupplies high frequency power to the semi-open saddle type highfrequency induction heating coil 5 from a power source (not shown), andthree guide chips 21 a, 21 b and 21 c for high frequency inductionheating coil which are attached at predetermined positions of the sideplate 7 in correspondence with the semi-open saddle type high frequencyinduction heating coil 5 (in the present embodiment, at three places ofthe upper side portion with respect to the center line of the journalportion 2 of the crankshaft 1, and of the left and right side portionswith respect to the center line of the journal portion 2). Furthermore,the high frequency induction heating apparatus 20 is provided withcooling water supply means 10 for spraying cooling water for hardeningtreatment to the journal portion 2 which is subjected to high frequencyinduction heating by the semi-open saddle type high frequency inductionheating coil 5. Note that FIG. 2 is a front view of the side plate 7 forrepresenting the structure of the three guide chips 21 a, 21 b and 21 cfor high frequency induction heating coil, which are main components ofthe present embodiment.

The three guide chips 21 a, 21 b and 21 c for high frequency inductionheating coil are respectively attached between the pair of side plates 7and 7 for supporting the semi-open saddle type high frequency inductionheating coil 5. The three guide chips 21 a, 21 b and 21 c are arrangedso as to be brought into contact with the upside portion and the leftand right side portions of the journal portion 2 of the crankshaft 1which journal portion is driven and rotated about the center line of thejournal portion 2 by a rotary drive mechanism (not shown), in order tosecure a predetermined gap between the journal portion 2 and thesemi-open saddle type high frequency induction heating coils 5 at thetime when the journal portion 2 is subjected to high frequency inductionheating by the semi-open saddle type high frequency induction heatingcoil 5. Specifically, as shown in FIG. 1 and FIG. 2, one guide chip 21 aamong the three guide chips 21 a, 21 b and 21 c for high frequencyinduction heating coil is arranged at the upper side portion withrespect to the center line of the journal portion 2 of the crankshaft 1,while the other two guide chips 21 b and 21 c for high frequencyinduction heating coil are arranged at the left and right side portionswith respect to the center line of the journal portion 2. Furthermore,when the three guide chips 21 a, 21 b and 21 c for high frequencyinduction heating coil are brought into contact with the outerperipheral surface of the journal portion 2, the center of the journalportion 2 is positioned with respect to the semi-open saddle type highfrequency induction heating coil 5.

FIGS. 3( a) and 3(b) show a detailed structure of the guide chip 21 afor high frequency induction heating coil, which is used in the highfrequency induction heating apparatus 20. FIG. 3( b) is a side view ofthe guide chip 21 a for high frequency induction heating coil. FIG. 3(a) is a sectional view taken along the line A-A in FIG. 3( b). Note thatthe arrangement positions and directions of the other guide chips 21 band 21 c for high frequency induction heating coil are different fromthose of the guide chip 21 a for high frequency induction heating coil,but the structure of the guide chips 21 b and 21 c for high frequencyinduction heating coil is substantially the same as the structure of theguide chip 21 a for high frequency induction heating coil. Thus, thedescription of the structure of the guide chips 21 b and 21 c isomitted.

As shown in FIG. 2, a semicircular arc-shaped opening portion 22, inwhich the journal portion 2 of the crankshaft 1 is inserted andarranged, is foamed in the lower portion of the side plates 7 and 7. Thedistal end portions of the guide chips 21 a, 21 b and 21 c for highfrequency induction heating coil, which are configured as shown in FIGS.3( a) and (b), are arranged so as to project into the above-describedsemicircular arc-shaped opening portion 22, at the upper side portionand the left and right side portions of the semicircular arc-shapedopening portion 22 of the side plates 7 and 7 (that is, at the upperportion with respect to the center line of the journal portion 2 and atthe left and right portions with respect to the center line). Morespecifically, at the upper side portion of the semicircular arc-shapedopening portion 22 of the side plates 7 and 7, there are respectivelyformed a pair of slits 23 and 23 which are extended upward from thesemicircular arc-shaped opening portion 22 so as to be in parallel witheach other, so that the portion between the pair of slits 23 and 23 (acantilever supported plate-shaped body having a spring function) isprovided as a flexible body 24 a. At the left and right side portions ofthe semicircular arc-shaped opening portion 22 of the side plates 7 and7, there are formed a slit 25 and a slit 26 which are respectivelyextended from the semicircular arc-shaped opening portion 22 to the leftand right sides thereof, and the side plate portions respectivelyadjacent to the slits 25 and 26 are provided as flexible bodies 24 b and24 c. Furthermore, the guide chip 21 a for high frequency inductionheating coil is attached between the flexible bodies 24 a and 24 a ofthe side plates 7 and 7, and the guide chips 21 b and 21 c for highfrequency induction heating coil are respectively attached between theflexible bodies 24 b and 24 b of the side plates 7 and 7, and betweenthe flexible bodies 24 c and 24 c of the side plates 7 and 7. Therefore,in the present embodiment all of the three guide chips 21 a, 21 b and 21c for high frequency induction heating coil are configured so as to beflexible. Note that reference numerals 27 and 27 in FIG. 1 denoteauxiliary side plates, and one slit 25 and one slit 26 are provided toeach of the side plates 7 and 7 (see FIG. 2). However, the presentinvention is not limited to this configuration, and as in the case ofthe above-described slits 23 and 23, it may also be configured such thattwo mutually parallel slits are provided to the side plates 7 and 7 soas to sandwich each of the flexible bodies 24 b and 24 c.

On the other hand, as shown in FIG. 1 to FIG. 4, the guide chip 21 a fora high frequency induction heating coil comprises the pair of mutuallyfacing flexible bodies (flexible plates) 24 a and 24 a which are madeflexible by the slits 23 and 23, chips 29 a and 29 a which arerespectively fixed in close contact with the inner surfaces of theflexible bodies 24 a and 24 a, and the distal end sides of which areexpanded from the flexible bodies 24 a and 24 a and arranged to projectfrom the outer surface of the flexible bodies 24 a and 24 a, and chipfixing plates 30 a and 30 a which are respectively fixed in closecontact with the inner surface of the chips 29 a and 29 a. Also, each ofthe fixing of the flexible bodies 24 a and 24 a, the fixing of the chips29 a and 29 a, and the fixing of the chip fixing plates 30 a and 30 a isseparately performed by each pair of screws 31 a and 31 a at positionsfacing each other. Note that the side plate 7 and the flexible body 24 aare made of a copper alloy for a spring (phosphor bronze, berylliumcopper, or the like, in the present embodiment). The chip fixing plate30 a is mainly made of a brass material, and the chip 29 a is made ofceramic. However, the present invention is not limited to these.

Furthermore, as shown in FIG. 3( a), in the guide chip 21 a for a highfrequency induction heating coil, a gap 32 is formed between the innersurfaces of the chip fixing plates 30 a and 30 a in a free state inwhich the guide chip 21 a is not inserted between the adjacentcounterweight portions 3 and 3. The flexible body 24 a is made flexiblein the direction of reducing the gap 32 by using, as a fulcrum, aposition indicated by reference character P in FIGS. 3( a) and 3(b).Thus, the flexible bodies 24 a and 24 a, and also the chips 29 a and 29a and the chip fixing plates 30 a and 30 a which are respectivelyseparately fixed to the flexible bodies 24 a and 24 a with the screws 31a and 31 a, are configured so as to be flexible by using, as a fulcrum,the position indicated by reference character P, and configured to beelastically deformed by the elasticity of the flexible bodies 24 a and24 a. Note that the width dimension W₁ (see FIG. 3( a) and FIG. 4( a))between the external surfaces of the chips 29 a and 29 a is set tobecome larger than the width dimension L₂ (see FIG. 4( a), FIG. 4( b)and FIG. 9) of the journal portion 2 of the crankshaft 1 at the timewhen the guide chip 21 a for high frequency induction heating coil is inthe free state as shown in FIG. 3( a). In this case, when the width ofthe gap 32 in the free state is set as W₂ (see FIG. 3( a) and FIG. 4(a)), the width W₂ is set to satisfy the formula: (W₁−L₂)≦W₂.

On the other hand, the structure of the guide chips for a high frequencyinduction heating coil, which are used when applying high frequencyinduction heating to the pin portion 4 of the crankshaft 1, is also thesame as the above-described structure of the guide chip 21 a for a highfrequency induction heating coil, and hence the description thereof isomitted. Of course, for the pin portion 4 of the crankshaft 1, the widthdimension (not shown) between the outer surfaces of a pair of chips ofthe guide chip for high frequency induction heating coil, is set largerthan the width dimension L₃ (see FIG. 9) between the counterweightportions 3 and 3 on both sides of the pin portion 4.

Next, there will be described an operation at the time when the journalportion 2 of the crankshaft 1 is subjected to high frequency-inductionheating by the high frequency induction heating apparatus 20 includingthe guide chips 21 a, 21 b and 21 c for high frequency induction heatingcoil, so as to be hardened. First, in order to apply high frequencyinduction heating to the journal portion 2 of the crankshaft 1, the highfrequency induction heating apparatus 20 is moved downward by a liftingmechanism (not shown) so that the journal portion 2 is arranged in thesemicircular arc-shaped opening portion 22 of the side plate 7. Thereby,the distal end portions of the guide chips 21 a, 21 b and 21 c for highfrequency induction heating coil (for example, distal end portions ofthe pair of chips 29 a and 29 a) are inserted between the counterweightportions 3 and 3 of the crankshaft 1, so as to be brought into contactwith the outer peripheral surface of the journal portion 2. As describedabove, the width dimension W₁ of the guide chips 21 a, 21 b and 21 c forhigh frequency induction heating coil in the free state is set largerthan the width dimension L₂ between the counterweight portions 3 and 3of the journal portion 2 (W₁>L₂) (see FIG. 4( a)), and hence, at thistime, the flexible bodies 24 a and 24 a, and the like, are elasticallydeformed by using, as a fulcrum, the position indicated by referencecharacter P (see FIG. 3( a) and FIG. 3( b)). Thereby, the width of thegap 32 in each of the guide chips 21 a, 21 b and 21 c is reduced to beless than the width W₂ of the gap 32 in the free state, so as to becomea width W₃. In this case, the flexible body 24 a is elastically deformedto reduce the gap 32, and hence each of the pairs of the chips 29 a and29 a, and the like, of the guide chips 21 a, 21 b and 21 c for highfrequency induction heating coil are brought into press contact with theinner surfaces of the counterweight portions 3 and 3 on both sides ofthe journal portion 2 by the elastic restoring force (elastic force inthe direction of increasing the width W₃) of each of the pairs of theflexible bodies 24 a and 24 a, and the like. As a result, the guidechips 21 a, 21 b and 21 c for high frequency induction heating coil andthus the semi-open saddle type high frequency induction heating coil 5are positioned at a correct position in the width direction of thejournal portion 2. That is, the semi-open saddle type high frequencyinduction heating coil 5 is positioned at the center position in thewidth direction of the journal portion 2 between the mutually adjacentcounterweight portions 3 and 3.

In such a state, the crankshaft 1 is driven and rotated about the axisline thereof (the center line of the journal portion 2) by the rotarydrive mechanism (not shown). Also, the high frequency induction heatingapparatus 20, and thus the guide chips 21 a, 21 b and 21 c, and thesemi-open saddle type high frequency induction heating coil 5 are heldby a high frequency induction heating coil following mechanism (notshown) so as to follow the rotating journal portion 2. Thereby, thejournal portion 2 is subjected to high frequency induction heating bythe semi-open saddle type high frequency induction heating coil 5.Thereafter, a hardening treatment is performed by spraying cooling waterfrom the cooling water supply means 10 to the outer peripheral surfaceof the journal portion 2 which is high-frequency induction heated to arequired hardening temperature, so that a hardened case is formed.

FIG. 5 shows a hardened case S₃ which is formed at the time when aportion 35 without an oil hole 34 in the journal portion 2 is subjectedto high frequency induction heating so as to be hardened by using theguide chips 21 a, 21 b and 21 c for high frequency induction heatingcoil. FIG. 6 shows a hardened case S₄ which is formed at the time when aportion 37 with an oil hole 36 in the journal portion 2 is subjected tohigh frequency induction heating so as to be hardened by using the guidechips 21 a, 21 b and 21 c for high frequency induction heating coil.Furthermore, FIG. 7 shows non-hardened areas in the portion 35 shown inFIG. 5, and FIG. 8 shows non-hardened areas in the portion 37 shown inFIG. 6. Note that in FIG. 7 and FIG. 8, the horizontal axis representsthe hardening portion, and the vertical axis represents the non-hardenedarea. The standard value of the non-hardened area is set in a range of3.0 to 4.5 mm. Furthermore, in FIG. 7 and FIG. 8, the □ mark representsa case in which the conventional guide chips 8 a, 8 b and 8 c (see FIG.12) for high frequency induction heating coil are used, and the ⋄ markand the ◯ mark represent cases in which the guide chips 21 a, 21 b and21 c for high frequency induction heating coil according to the presentembodiment are used. In the figures, the ⋄ mark represents a case inwhich the flexible bodies 24 a and 24 a having a low spring constant(spring constant=5.9 kg/mm) are used, while the ◯ mark represents a casein which the flexible bodies 24 a and 24 a having a high spring constant(spring constant=7.8 kg/mm) are used. Here, the point represented byeach of the □ mark, the ⋄ mark, and the ◯ mark corresponds to an averagevalue in the non-hardened area. Also, the upper end of the straight lineextended upwards from each of the marks corresponds to a maximummeasured value in the non-hardened area, while the lower end of thestraight line extended downwards from each of the marks corresponds to aminimum measured value in the non-hardened area. On the other hand, thehardening portions are the second journal portion 2 (2J) from the leftof the crankshaft 1 shown in FIG. 9 and the fourth journal portion 2(4J) from the left of the crankshaft 1 shown in FIG. 9. Note that thediameter of the second journal portion 2 (2J) is 76.8 mm and the widththereof is 24.0 mm, while the diameter of the fourth journal portion 2(4J) is 76.8 mm and the width thereof is 23.5 mm. Therefore, the fourthjournal portion 2 (4J) has a width dimension slightly smaller (−0.5 mm)than that of the second journal portion 2 (2J).

As shown in FIG. 7, it can be seen that in the case in which theconventional guide chips 8 a, 8 b, and 8 c for high frequency inductionheating coil are used, the lower limit value of the non-hardened area ofthe second journal portion 2 (2J) is smaller than the lower limit valueof the specification, and that the non-hardened area of the fourthjournal portion 2 (4J) is barely within the range of the specification.On the other hand, it can be seen from the figure that in the case inwhich the guide chips 21 a, 21 b and 21 c for high frequency inductionheating coil according to the present embodiment are used, thenon-hardened area of the journal portion is sufficiently within therange of the specification. Furthermore, the variation in thenon-hardened area tends to become comparatively large in the portion 37with the oil hole 36 in the journal portion 2. However, it can be seenfrom FIG. 8 that in the case in which the guide chips 21 a, 21 b and 21c for a high frequency induction heating coil according to the presentembodiment are used even for the portion 37 with the oil hole 36 in thejournal portion 2, the non-hardened area is sufficiently within therange of the specification.

Note that FIGS. 5 and 6 show hardened cases S₃ and S₄ formed in the casein which the guide chips 21 a, 21 b and 21 c for high frequencyinduction heating coil according to the present embodiment are used, andit is confirmed from the figures that the hardened cases S₃ and S₄ areformed at substantially correct positions in both the portion 35 withoutthe oil hole 34 and the portion 37 with the oil hole 36 in the journalportion 2.

In the above, an embodiment according to the present invention has beendescribed. However, the present invention is not limited to theembodiment, and various modifications and changes can be made within thescope and spirit of the present invention. For example, in theabove-described embodiment, it is configured such that the journalportion 2 of the crankshaft 1 is subjected to high frequency inductionheating so as to be hardened by using the guide chips 21 a, 21 b and 21c for high frequency induction heating coil, but the present inventioncan also be applied to the case in which the pin portion 4 of thecrankshaft 1 is subjected to high frequency induction heating so as tobe hardened by using the guide chips 21 a, 21 b and 21 c for highfrequency induction heating coil. Furthermore, in the above-describedembodiment, the three guide chips 21 a, 21 b and 21 c for high frequencyinduction heating coil are configured in a flexible manner, but only oneof the guide chips may be configured in the flexible manner. Also inthis case, the guide chips for high frequency induction heating coil,and thus the semi-open saddle type high frequency induction heatingcoil, can be correctly positioned in the width direction of the journalportion or the pin portion. Furthermore, in the above-describedembodiment, it is configured such that the three guide chips 21 a, 21 band 21 c for high frequency induction heating coil are used, but it ispossible to use two or four or more guide chips for high frequencyinduction heating coil. Furthermore, in the above-described embodiment,it is set such that the width of the gap 32 between the chip fixingplates 30 a and 30 a facing each other is reduced to become the width W₃at the time when the guide chips 21 a, 21 b and 21 c for high frequencyinduction heating coil are inserted between the mutually adjacentcounterweight portions 3 and 3 (see FIG. 4( b)). However, it may also beset such that the width of the gap 32 is reduced to become zero (the gap32 is eliminated) at that time. In the above, there has been describedthe structure of the guide chips for high frequency induction heatingcoil according to the present invention. However, the guide chipstructure is not limited to the above-described structure, and it isobvious that those included in the technical scope of the presentinvention can be applied.

1. A structure of a plurality of guide chips for high frequencyinduction heating coil, which are respectively attached between a pairof side plates for supporting a semi-open saddle type high frequencyinduction heating coil, which, when a journal portion or a pin portionof a crankshaft is subjected to high frequency induction heating by thesemi-open saddle type high frequency induction heating coil, are usedfor positioning the center of the journal portion or the pin portionwith respect to the semi-open saddle type high frequency inductionheating coil, and which are used for positioning the semi-open saddletype high frequency induction heating coil in the width direction of thejournal portion or the pin portion between mutually adjacentcounterweight portions of the crankshaft, the structure beingcharacterized in that the guide chip for high frequency inductionheating coil includes: a pair of flexible bodies which have a springfunction and which are respectively provided in the pair of side plates;a pair of chips which are respectively arranged and fixed in the insideof the pair of flexible bodies facing each other; and a pair of chipfixing plates which are respectively arranged and fixed in the inside ofthe pair of chips, and characterized by being configured such that, in afree state in which the guide chip for high frequency induction heatingcoil is not inserted between the mutually adjacent counterweightportions, a gap exists between the inner surfaces of the pair of chipfixing plates facing each other, and also the width dimension betweenthe outer surfaces of the pair of chips facing each other is set tobecome larger than the width dimension of the journal portion or the pinportion, and such that when the guide chip for high frequency inductionheating coil is inserted between the mutually adjacent counterweightportions, the gap between the inner surfaces of the pair of chip fixingplates is reduced or eliminated by the spring function of the pair offlexible bodies.
 2. The structure of the guide chips for high frequencyinduction heating coil according to claim 1, characterized in that theflexible body is integrally provided to the side plate by forming, inthe side plate, a pair of slits that are arranged at a distance so as toface each other and extended to an opening portion of the side plate inwhich opening portion the journal portion or the pin portion is insertedand arranged.
 3. The structure of the guide chips for high frequencyinduction heating coil according to one of claim 1 and claim 2,characterized in that the guide chips for high frequency inductionheating coil are arranged at three places of the upper side and the leftand right sides with respect to the center line of the journal portionor the pin portion, and in that the flexible body is provided at all orat least one of the three places in which the three guide chips for highfrequency induction heating coil are arranged.